Gravity fed ditches formed in earth for conveying water to a point or location for use has been in common use for generations throughout the world. As used in this document, the term “ditch” includes any excavation dug in earth that also may be referred to as a drain, channel, canal or acequia. Ditches have, and continue to be, used to transport both potable and irrigation water. Earthen irrigation ditches continue to be significant transporters of water, particularly to convey surface irrigation water to crops. Earthen ditches, relying on principles of gravity flow to transport water along descending elevations of a ditch, continue to be popular because they provide low-cost irrigation systems.
As provided in U.S. Pat. No. 6,273,640 B1 issued on Aug. 14, 2001, to Kenneth L. Suazo, U.S. Pat. No. 6,692,186 B1 issued on Feb. 17, 2004 to Suazo, et al., and U.S. Pat. No. 6,722,818 B1 issued on Apr. 20, 2004, (collectively, the “Earlier Suazo Patents”), concrete is a common material used to line earthen ditches. Concrete, however, as also shown in the Earlier Suazo Patents, have several material deficiencies and limitations, including material inconsistencies, cracking, and failure that lead to considerable water loss due to seepage, erosion, evaporation, and trans-evaporation. Water is becoming an ever more precious and valuable resource and commodity; water loss is unacceptable. Water uses continue to increase, while the finite amount of available water does not. Installation and use of the apparatus and methods for reducing water loss disclosed and claimed in the Earlier Suazo Patents renders loss of water not only unacceptable, but also unnecessary.
The improved ditch liner system disclosed and claimed in this document makes further optimizations and contributions to the art disclosed and claimed in the Earlier Suazo Patents. Alternative features and elements disclosed and claimed in this document include at least the capacity of the improved ditch liner to further reduce water loss during transportation of water through ditches that have been lined with the improved ditch liner. The improved ditch liner system also ensures a water-tight connection between interconnected improved ditch liner sections, while enhancing the flow of water through the improved ditch liners. The improved ditch liner system may be installed either permanently or temporarily in either concrete lined ditches or earthen ditches. The improved ditch liner system is easy to install, lightweight, and will transport water at greater efficiency while, as stated, while reducing loss of water during conveyance. The improved ditch liners also reduces maintenance problems accompanying insiltation, cleaning and maintenance of conventional concrete lined ditches and earthen ditches. The improved ditch liner system is durable, flexible, and cost-effective. The improved ditch liner system, therefore, provides efficient management and conservation of surface water.
At least one contribution to the art made by the improved ditch liners and improved ditch liner system disclosed and claimed in this document is its capability to overcome undersirable effects of friction between (i) a boundary of a moving body of water in contact with, and moving through a ditch liner system, and (ii) the inner surface of the improved ditch liner. The term “friction” as used in this document means the force of resistance caused by one surface on another. Forces of resistance tend to prevent or retard slipping or movement of the water along a ditch liner. Forces of resistance may also cause damage to a ditch liner and to a ditch liner system.
As is known to those skilled in the art, forces of resistance always act tangentially to a surface at points of contact with the surface. Further, the force is a function of, or proportional to, the normal force, and is exposed as the “coefficient of static friction” in a stationary body, or “coefficient of kinetic friction” in a moving body. A coefficient of friction is a dimensionless number that depends on characteristics of the contacting surfaces, or in this instance, the characteristics of the boundary of a moving body of water, and the contact surface of the improved ditch liner. It is known that the coefficient of friction varies with temperature, humidity, pressure, the materials in contact, the sliding velocity of the body moving in relation to a surface, and whether the body and surface are dry or lubricated. It also is known to those skilled in the art that when two surfaces, or a boundary and a surface, move relative to each other, a lateral force is required to overcome adhesion, a force is referred to as “adhesional friction force.” It also is known that the contacts between surfaces moving relative to each other depend primarily on the surface topography and the mechanical properties of the mating surfaces.
To overcome undesirable results of such forces and coefficients, studies and experimentation confirmed the usefulness of reconfiguring the radial geometry of corrugations in the improved ditch liner. The novel tightly-peaked radial geometry of corrugations used in the improved ditch liner section substantially improves flow efficiency by altering undesirable coefficients, including the Manning resistance coefficients. Lowering the Manning resistance coefficients by use of the arc-and -ridge corrugations of the improved ditch liner was an unexpected result.
To achieve a substantially zero-loss water-tight seal between interconnectable nested ends of the improved ditch liner, the inventors also determined that a number of features could contribute to that goal. Corrugations extend substantially the entire length of each improved ditch liner section. The material used to manufacture each improved ditch liner section is the same; restated, different materials are not combined to make the improved ditch liner. Demountably interconnectable male-female opposing ends of each improved ditch liner section are formed with a channel into which a hydrophilic sealant, such as a vulcanized rubber hydrophilic seal, may be inserted. To reduce costs associated with manufacturing the improved ditch liner sections, the process of manufacturing is a rotational molding process, although a watertight seal using a plastic material has not previously been achieved using rotational molding.